The homework is usually not over 30 minutes, and it helps the students to focus on their classroom work. In grade school the students usually don't study more than 30 - 35 minutes per assignment.
They have art, physical education, library, and computer classes. They also have lunch and outdoor play time. Research has shown that the kids need a longer day than most parents think. Practice makes perfect.
Parents need to participate with their kids homework. They need to know the trends and topics that their child is studying, and if they are getting their work done. You should not just be hearing their progress from the teacher only. By working with your child, you will know if they have problems and try to work with them.